3. The best sightings of the northern lights often __ between 11pm and midnight. D. host A. locate B. occur C. measure A. paradises B. ecosystems 4. Tourists couldn't __ admiring the magnificent view of the Victoria Falls. D. permit A. think B. encourage C. help 5. Grand Canyon South Rim offers easy __ to the most beautiful viewpoints of the area. D. possession A. permission B. access location 6. The trip to explore Son Doong Cave is very __ It needs a lot of equipment and thorough preparation. D. threatened A. urgent B. charming C. risky 7. Kiwi birds and Hector'dolphins are some of the most signature __ of New Zealand. D. plant A. destination B. fauna C. flora 8. Conservationists announce that the giant pandas of China are an endangered __ D. series A. pieces B. species C. means gems like the Shinjuku Gyoen National Garden, a refuge teeming with diverse __ and fauna. A. plants D. trees B. flowers C. flora 10. Whale watching tours allow people to observe these giant mammals in their natural __ environment. A. land D. marine B. grassy C. desert 11. Some underwater caves near ancient Mayan ruins can only be explored through __ D. snorkeling A. windsurfing B. scuba diving C. sailing 12. You would look for a __ to learn more about things to do and places to stay at a tourist attraction. A. science journal B. arts magazine C. travel brochure D. daily newspaper 13. Rainforests are known for their incredible __ , with millions of species of insects, birds, and plants all living together A. climate change B. biodiversity C. deforestation D. weather patterns 14. Many parts of Mongolia are covered in __ where horses and sheep roam freely. A. swamp B. jungle C. ice sheet D. grassland 15. The Amazon rainforest is a complex __ with millions of plant and animal species depending on eac other for survival. A. collection B. ecosystem C. territory D. landscape 16. The limestone formation of Thien Duong Cave is more __ than that of Phong Nha Cave. D. annual A. spectacular B. probable C. biological 17. Visitors to Grand Canyon National Park can hike, raft, or take a helicopter tour to __ the park's stunning landscape. A. discover B. locate C. consider D. explore 18. The worker asked the manager if he __ the promotion the following month. A. have received B. had received C. would receive D. will receive 19. She wondered whether I __ home late the night before. A. have come B. had come C. would come D. was coming

Here are the answers and explanations for the fill-in-the-blank questions:<br /><br />**3. The best sightings of the northern lights often __ between 11pm and midnight.**<br /><br />* **B. occur** - The word "occur" means to happen or take place. It fits the context of the sentence, which is talking about when the northern lights are visible.<br /><br />**4. Tourists couldn't __ admiring the magnificent view of the Victoria Falls.**<br /><br />* **C. help** - The phrase "couldn't help" means to be unable to prevent oneself from doing something. It's used to express that the tourists were so impressed by the view that they couldn't stop admiring it.<br /><br />**5. Grand Canyon South Rim offers easy __ to the most beautiful viewpoints of the area.**<br /><br />* **B. access** - "Access" means the ability to approach or enter a place. It makes sense in the context of the sentence, which is talking about how easy it is to get to the viewpoints.<br /><br />**6. The trip to explore Son Doong Cave is very __. It needs a lot of equipment and thorough preparation.**<br /><br />* **C. risky** - "Risky" means dangerous or involving a possibility of loss or harm. This fits the context of the sentence, which describes the challenges of exploring Son Doong Cave.<br /><br />**7. Kiwi birds and Hector's dolphins are some of the most signature __ of New Zealand.**<br /><br />* **B. fauna** - "Fauna" refers to the animals of a particular region or period. It's the correct word to use when talking about the animals of New Zealand.<br /><br />**8. Conservationists announce that the giant pandas of China are an endangered __.**<br /><br />* **B. species** - "Species" refers to a group of living organisms that can reproduce with each other. It's the correct word to use when talking about the giant panda.<br /><br />**9. Tokyo is a city that offers a wide range of attractions, including cultural gems like the Shinjuku Gyoen National Garden, a refuge teeming with diverse __ and fauna.**<br /><br />* **C. flora** - "Flora" refers to the plants of a particular region or period. It's the correct word to use when talking about the plants in the Shinjuku Gyoen National Garden.<br /><br />**10. Whale watching tours allow people to observe these giant mammals in their natural __ environment.**<br /><br />* **D. marine** - "Marine" refers to the sea or ocean. It's the correct word to use when talking about the environment where whales live.<br /><br />**11. Some underwater caves near ancient Mayan ruins can only be explored through __.**<br /><br />* **B. scuba diving** - "Scuba diving" is the activity of diving underwater using scuba gear. It's the only option that makes sense in the context of exploring underwater caves.<br /><br />**12. You would look for a __ to learn more about things to do and places to stay at a tourist attraction.**<br /><br />* **C. travel brochure** - A "travel brochure" is a printed leaflet that provides information about a particular destination. It's the most likely source of information about things to do and places to stay.<br /><br />**13. Rainforests are known for their incredible __, with millions of species of insects, birds, and plants all living together.**<br /><br />* **B. biodiversity** - "Biodiversity" refers to the variety of life in a particular habitat or ecosystem. It's the correct word to use when talking about the diversity of species in rainforests.<br /><br />**14. Many parts of Mongolia are covered in __ where horses and sheep roam freely.**<br /><br />* **D. grassland** - "Grassland" is an area of land covered in grass. It's the most likely type of terrain where horses and sheep would roam freely.<br /><br />**15. The Amazon rainforest is a complex __ with millions of plant and animal species depending on each other for survival.**<br /><br />* **B. ecosystem** - An "ecosystem" is a community of living organisms and their physical environment. It's the correct word to use when talking about the interconnectedness of life in the Amazon rainforest.<br /><br />**16. The limestone formation of Thien Duong Cave is more __ than that of Phong Nha Cave.**<br /><br />* **A. spectacular** - "Spectacular" means impressive or magnificent. It's the best word to use when comparing the beauty of the two caves.<br /><br />**17. Visitors to Grand Canyon National Park can hike, raft, or take a helicopter tour to __ the park's stunning landscape.**<br /><br />* **D. explore** - "Explore" means to travel through or around a place in order to learn about it. It's the most appropriate word to use in the context of visiting the Grand Canyon.<br /><br />**18. The worker asked the manager if he __ the promotion the following month.**<br /><br />* **C. would receive** - The sentence is in the past tense, so we need to use the conditional "would receive" to express a future event from the worker's perspective in the past.<br /><br />**19. She wondered whether I __ home late the night before.**<br /><br />* **B. had come** - The sentence is in the past tense, and the action of coming home happened before the time of wondering. Therefore, we need to use the past perfect tense "had come". <br />